is there any way to get Mathematica to present it in it's real form? like

$\frac{a}{\sqrt{d-c}}$

I know that I can simply take Re[f[x]] to get the real part, but I don't just want the real part. If the answer is complex, I definitely want to know that, but when it is not complex and can be written as a fully real number, I would like it to give me that form.

My actual is example is far more complicated than this and the inside of the radical will always be positive if it is written as d - c, but I don't think i can put that assumption in because it is so complicated.

Mathematica is a registered trademark of Wolfram Research, Inc. While the mark is used herein with the limited permission of Wolfram Research, Stack Exchange and this site disclaim all affiliation therewith.